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Slide Rules

Index by Makers & Retailers

Hundreds of companies around the world were involved in the production of slide rules from the 18th to the 20th centuries. Click on one of the names below to see the objects in this collection that were associated with that firm.

This 9-1/2 inch paper linear slide rule was used to calculate the retail price that should be charged for an item (such as a box of General Foods cereal), given the wholesale cost of a case of packages of the item, the number of packages in the case, and the percentage of profit desired on the selling price. The top of the base has a scale for wholesale costs per unit, ranging from 50 cents to $7.50. The slide has scales for the number of retail packages in a unit, ranging from 10 to 150, and for the percentage of profit from 0% to 60%. The slide also has a table for the mark-up margin as a percentage of cost and as a percentage of selling price. The table is only visible by removing the slide from the base. The bottom of the base has a scale for retail selling prices, ranging from 3 to 45.

The base is marked: GENERAL FOODS PROFIT CALCULATOR (/) Copyrighted 1932. The slide is marked: Calculator (/) Scale (/) Copyrighted (/) 1932 (/) Walter T. (/) Scott (/) Phila., Pa. Instructions appear on the back of the slide. The back of the base has an advertisement depicting six boxes of C. W. Post cereals. It is marked: It Pays to Push POST CEREALS. It is also marked 3630 — Printed in U.S.A.

Formed in 1895 in Battle Creek, Mich., as the Postum Cereal Company and offering products such as Grape Nuts, the manufacturer had acquired at least eleven other food companies by 1929. Most importantly, Postum purchased General Foods Company from Clarence Birdseye and renamed the entire operation General Foods Corporation. From 1932, General Foods distributed this rule to grocers as an encouragement to more prominently display its cereals. Scott, who designed the rule, made improvements in 1940. By the 1940s, the advertisement on the back of the rule was replaced with advice on "How to Stay on the Profit Side." General Foods was purchased by Philip Morris in 1985 and subsequently merged with Kraft Foods.